DE1755787A1 - Pressure medium distributor for controlling a pressure medium brake - Google Patents

Description

Compagnia Italiana Westinghouse Freni E Segnali Turin, Italy

Pressure medium distributor for controlling a pressure medium brake.

The present invention relates to a pressure medium distributor for controlling a pressure medium brake, consisting of an output line connected to a brake cylinder and a brake control device, which depends on the pressure prevailing between the brake control line and a control pressure Pressure difference can be actuated, whereby an auxiliary pressure medium reservoir with the output line for the actuation of the brake on the one hand and the output line with an outlet opening

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for the release of the brake on the other hand can be associated.

There are two types of pressure fluid distributors for brakes - in particular for use on railroad cars-known generally as "direct" and "gradual" brake release systems can be designated. With both types of pressure fluid distributors the pressure prevailing inside the brake cylinder during the braking process is a puncture of the inside existing pressure in the brake control line · However, the two pressure medium distributors differ from one another! ■ With regard to the subsequent brake release,

With the direct brake release, the brake is released through an increase in the pressure within the brake control line causes the brake cylinder to be completely discharged, even if the pressure increase within the brake control line does not exceed a certain value. A full discharge With this system, the brake cylinder can only be prevented by actuating the brake again. As a result, it is in the generally in a system with direct brake release it is necessary to apply the brake repeatedly, whereby in the Intermediate intervals results in a partial brake release. Only in this way can a certain braking strength be achieved, as well as this is necessary, for example, when the railroad cars roll down a sloping slope. With this type will

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the pressure medium distribution solely through two pressures, i.e. the pressure existing within the control line and the pressure within an auxiliary reservoir existing pressure controlled, which auxiliary reservoir supplies a pressure medium to the brake cylinder during the braking process. The transition hangs while the system is in operation from the brake actuation to the brake release solely from the existing pressure difference between the pressure in the Brake control line and the pressure in the auxiliary reservoir. The inside The pressure prevailing in the brake cylinder, on the other hand, in no way affects the mode of operation of this type of pressure medium distributors.

In the case of a pressure medium distributor with gradual brake release, on the other hand, this is caused by an increase in the pressure in the brake control line Triggered brake release controlled as a puncture of the pressure increase in the brake control line. The size of the emptying of the brake cylinder can thus be adjusted, with the system can be designed in such a way that the brake cylinder is not completely emptied, although the brake engaging or releasing brake control valve is actuated. In braking systems of this type, the pressure medium distribution is controlled by three pressures - i. the pressure prevailing within the brake control line in a container called a control reservoir constant pressure and the pressure prevailing in the brake cylinder. When the brake is released, that pressure acts on the basis of which the pressure medium is transferred from the auxiliary reservoir to the brake cylinder when braking is supplied, instead of the one provided in the brake control line

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existing pressure, so that the size of the emptying of the brake cylinder is dependent on the pressure prevailing within the auxiliary reservoir. With this arrangement, the brake cylinder cannot be completely emptied as long as there are no leaks in the control reservoir.

Pressure fluid distributors with gradual brake release are for driving down Very suitable on sloping slopes, as long slopes can be driven with full safety and with relatively simple operation depending on the set braking function. Such Systems are, however, disadvantageous for braking on a level track, since a non-negligible time is necessary for the brake release is. This is especially the case if the train is very long, since the emptying of each brake cylinder with the filling of a corresponding one Auxiliary reservoir is connected. The slowness of filling the auxiliary reservoir of the rear wagons of the train therefore leads to a corresponding delay in emptying the corresponding brake cylinders of these rear wagons.

Significant advances have been made in the past to expedite brake release in gradual discharge manifold systems. The filling of the auxiliary reservoir into the rear wagons of a train can thereby WDEN increased by performing, for example, a reduced air supply from the brake control lead to the in the front carriages of the train located auxiliary reservoirs or a prolonged charging of the system in terms of in the main

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Control reservoir prevailing pressure is made, while at the same time overloading the in the individual wagons in the rear Part of the train located auxiliary reservoir is avoided. The resulting brake release delay times for relative however, long trains are noticeably longer than those that are possible with pressure fluid distributors with direct brake release are.

Finally, it is still known, pressure medium distributors with direct Brake solution to be provided with devices that allow emptying of the breas cylinder at two different speeds, viz one fast and one slow, the emptying in accordance with the setting of a switching device he follows. However, such a system does not eliminate the need for cyclic Braß actuation on inclines, as there is no possibility of adjusting the size of the pressure within the brake cylinder to a certain level.

It is the aim of the present invention to provide a pressure medium distributor to create that allows a partial emptying of the brake cylinder in the manner of a gradual brake release when braking is done on sloping slopes and that is of the type of systems that can be operated with direct brake release, when braking on flat terrain is necessary. So it is the main object of the present invention to provide a switching device to create that the "workings of such a."

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combined braking system affected.

According to the invention, this is achieved in that a reversing valve is provided having a position for gradual brake release in which the control pressure is within a Druckraittelsteuerreservoirs prevailing pressure and the output line with one of the movement of the control element in the direction a brake actuation counteracting pressure medium actuation element is connected, and that the switching valve has a position for direct brake release, in which the control pressure is the pressure prevailing within an auxiliary reservoir, and the actuating element is rendered ineffective.

The distribution system according to the present invention is therefore a changeover to obtain and in relatively simple capable of actuating valves gate of the puncture manner a gradual braking operation with direct solution to the brake release and vice versa,

Such a switching valve can be operated by hand, but to facilitate the operation for the operator - ie the train driver - the switching valve can also be operated electrically by a remote control, for example. It should be noted that the use of electrical lines along the entire length of the train for the required electrical remote control is very easy to provide in the existing automatic pressure medium brake systems in which the

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Coupling between the individual wagons is known to be purely pneumatic Are nature. The additional installation of electrical connections between the individual wagons with the help of suitable In the future, the plug will be made easier by the introduction of automatic couplings in Europe, as these Couplings in addition to mechanical and pneumatic connections electrical connections are also provided.

The remote control of the switching valves can, however, also be purely pneumatic be undertaken by, for example, a brief change in pressure within the brake control line - for example by creating a certain vacuum - made are.

Further details of the invention are to be explained and described in more detail below on the basis of exemplary embodiments with reference to the accompanying drawing, it shows:

FIG. 1 shows a schematic view of the pressure medium circuit of a system according to the first embodiment of the invention in FIG the position for gradual brake release;

FIG. 2 shows a schematic view of the switching valve of the embodiment shown in FIG. 1 in the position of the direct Brake release;

Figure 3 is a shameful view - similar to Figure 1 -

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a modified embodiment of the invention in the position a gradual brake release;

FIG. 4 shows a schematic view of a switchover valve in FIG embodiment shown in Figure 3 in the position of the direct brake release;

FIG. 5 shows a schematic view - similar to FIG. 1 - of a further embodiment of the invention in the position of the gradual brake release; and

FIG. 6 is a schematic view of the switchover valve in FIG Embodiment shown in Figure 5 in the position of the direct brake release.

In the following, reference should be made to FIG. 1, which shows a pressure medium distributor with various actuation control elements, a drive piston 1 and a compensation piston 2 being provided, which are arranged in a sealed manner in corresponding cylinders. The pistons 1, 2 are connected to one another with the aid of a rod 3 and sealed by corresponding sealing rings. The chamber k located below the piston 2 is permanently connected to the outside atmosphere via an outlet opening 5.

The system also has an exit line 38, which is connected to a schematically indicated brake cylinder 21 is connected. An auxiliary reservoir 22 and a control reservoir 23 are provided with a pressure medium - i. E. in this case with compressed air - supplied with the pressure medium

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is kept constant in a predetermined pressure range.

A device connected to the control reservoir 23 is shown in FIG 1 arranged on the left side of the control unit and consists of an actuating piston 9 »which is sealed within of a cylinder is arranged. The one below the piston 9 The chamber contains a weak compression spring 10 and is in permanent communication with an outlet line 12. The piston 9 is also connected to a control reservoir fill valve I ^ by means of a rod 13.

A changeover valve 15 for performing the changeover from gradual for direct brake release contains a rotatable valve element which is arranged within a cylindrical tube and can optionally be pivoted into one of the two positions shown in FIGS. 1 and 2. For easier presentation the valve element is shown in three separate parts, an upper part with two opposing recesses 16, 17 a middle part with two opposing recesses 18, 19 and a lower part with a single recess 20.

A normally closed inlet valve 6 connects the outlet line 38 to the auxiliary reservoir 22. A discharge valve 7 fixedly connected to the inlet valve 6 engages the open end of a central bore [V) of the rod 3 Ln. The pipe 39 is permanently connected to an outlet opening at ^ O,

In Figure 1 ir, t the system with the switching valve. L5 Lu ^r -ioi * I'ohltion for gradual DrumM 'idim ^ durgestelLb, In (lUiser Ι'-ψ, α lon

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Valve 15 is compressed air from a brake control line 24 of the chamber 25 located above the drive piston 1, whereby the piston 1 with additional support a weak spring 26 arranged within the chamber 25 reaches its lowest position.

The air coming from the brake control line 24 flows from the Chamber 25 through a channel 27 and a recess 28 arranged inside the rod 3 to a conduit 29 and from there through a line 30, a recess 18 disposed within the switching valve 15, and a line 31 to a normally open pressure relief valve 8, which in turn is connected to the auxiliary reservoir 22 via a line.

At the same time, air flows from brake control line 24 through lines 29 and 32 to the lower surface of valve 14 of the control reservoir regulator. The valve 14 is in the open position, so that the piston 9 - as shown - is in its uppermost position due to the weak spring 10. The compressed air flows through the valve 14 via a calibrated constriction 33, a line 34, a recess 20 arranged within the rotating part of the switching valve 15 and a line to the control reservoir 23. From the recess 20, compressed air also flows through a line 36 to the one below des Antriebskolh <f.:na 1 of the control device lying chamber 37.

So.-! llea is shown, the system is not in

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activated state. The brake cylinder 21 is via the output line 38, through the bore 39 arranged within the rod 3 of the compensation piston 2 and the outlet line 40 with the outlet tied together. The brake cylinder 21 is also available via a line 41 with the lying above the piston 9 of the control reservoir regulator Chamber 32 in connection. The brake cylinder 21 is also via the outlet line 38, a line 43 which runs within the switching valve 15 arranged recess 16 and a line 44 with the chamber 45 located above the compensation piston 2 in connection. When the system receives the full actuation pressure of the brake control line 24, the drive piston 1 is through the inside the above and below the piston 1 lying chambers 25 and 37 - i.e. by the inside of the brake control line 27 and the Control reservoir 23 prevailing pressures - compensated.

The braking process is initiated as soon as a vacuum occurs within the brake control line 24. The existing in the control reservoir 23 and the chamber located below the drive piston 1, 37 compressed air flows back through the line 24, the calibrated restriction 33, the open valve 15, lines 32 and 29 _t the recess 28, the channel 27 and the chamber 25 to the brake control line 24. However, since there is a pressure difference between the chambers 37 and 25 because of the constriction 33, the piston 1 moves upwards.

The upward movement of the drive piston 1 lifts with the aid the rod 3 of the compensation piston 2 from; as soon as the open end

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the rod 3 comes into contact with the discharge valve 7 then the connection between the outlet line 38 and the outlet line 40 interrupted.

At the same time, the connection between the control reservoir 21 and the brake control line 24 is interrupted, since during the upward movement the rod 3, the recess 28 from the area of the Channel 27 arrives.

When the piston 1 is lifted further from the rod 3, the inlet valve 6 opens, so that compressed air is released from the auxiliary reservoir 22 passes through line 44, admission valve 6 and outlet line 38 to brake cylinder 21. At the same time The compressed air present inside the brake cylinder 21 also passes through the line 43, through the inside of the valve element of the switching valve 15 arranged recess 16 and the line 44 to the above the compensation piston 2 Chamber 45. This creates a downward force which is proportional to the brake cylinder pressure, this force acting on the piston 2, so that one of the brake release is opposite Movement arises.

After the brake cylinder pressure is relatively low, in general has reached a value lying at about 0.25 kg / cm, the piston 9 of the control reservoir regulator moves downwards. This is a closure of the pressure relief valve 14 with the help of

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Rod 13 is effective, so that an insulation of the control reservoir 21 and the chamber 37 located below the drive piston 1 from the brake control line 24 is reached. The pressure prevailing within the control reservoir 23 and the chamber 37 is then increased held essentially at the value intended for operation of the system.

As soon as the pressure prevailing inside the brake cylinder 21 and acting on the upper surface of the compensation piston 2 has reached a certain value in order to overcome the upward force acting on the rod 3 - which is created due to the vacuum that is created within the brake control line 24 and thus within the chamber 25 - prevails, the rod and both pistons 1 and 2 move downwards again until the inlet valve 6 is closed again. As a result, however, the supply of pressure medium to the brake cylinder 21 is interrupted. However, the discharge valve 7 remains closed, so that the outlet line is not connected to the outlet. This state is to be referred to in the following as the “neutral braking position ^{11 of} the rod 3.

Upon further drop of the pressure within the brake control cable 24, the piston 1 and the rod 3 raise again, that the inlet valve 6 is opened again, and compressed air is supplied to the brake cylinder 21 until the pressure within the latter corresponding to the decreased pressure within the conduit 24 appropriate

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has risen. This process continues until the inside of the auxiliary reservoir 22 and the pressures prevailing within the brake cylinder 21 are the same, at which point in time the The pressure prevailing within the brake cylinder 21 holds its maximum value.

In the event of a loss of pressure within the brake cylinder the prevailing pressure within the chamber 45 falls, so that the equilibrium of the opposite caused by the pistons 1 and 2 Forces is controlled and the rod 3 rises again. As a result, the inlet valve 6 is opened again until a sufficiently high pressure is restored, which brings about an equilibrium between pistons 1 and 2 and within the brake cylinder 21 restores the prevailing pressure to its original value.

The within the brake control line 24 and thus within the The pressure prevailing in chamber 25 is increased by the operator as soon as the brake is to be released again. The balance the Kiben 1 and 2 is then disturbed again, so that the rod 3 moves from its neutral position to the brake release position shown in FIG. The inside of the brake cylinder Compressed air present then escapes through the bore 39 arranged inside the rod and the outlet 40. Soabld the inside the chamber 45 on the surface of the com-

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Compensation piston 2 acting brake cylinder pressure dropped to a value is at which an equilibrium with respect to that prevailing within the brake control line 24 and thus the chamber 25 increased pressure is reached, the rod 3 returns to its neutral position again, so that the outlet valve again closed is.

The downward movement of the rod 3 in its release position is conditional a connection between the recess 28 provided within the rod 3 and the channel 27 leading to the chamber 25 " The compressed air present inside the brake control line 24 flows then through the chamber 25, the channel 27, the recess 23, the lines 29 and 30, the recess 18, the line 31 and the pressure relief valve 8 into the auxiliary reservoir 22.

As soon as the inside the chamber 42 above the piston 9 of the The brake cylinder pressure prevailing in the control reservoir regulating device has dropped to a value which causes the valve 14 to close if which - as has already been mentioned - is in the order of magnitude of 0.25 kg / cm, the piston 9 moves again under the action of the spring 10 upwards, with a renewed opening of the valve 14 being achieved and a connection between en the control reservoir 23 and the brake control line 24 again will be produced. The system has thus returned to the starting position shown in FIG.

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In the following, reference should be made to Figure 2, in which the switching valve 15 is shown in the position for direct brake release. You can see that the system is in this Position is different from the position shown in Figure 1. The prevailing within the control reservoir 23 constant Pressure is from line 36 and thus from chamber 3? separated, so that this pressure can no longer exert an effect on the operating state of the piston 1. The line 43 is separated from the line 44 by the valve 15, so that the brake cylinder 21 is no longer in communication with the chamber 45. The chamber 45, however, stands over the line 44 and the recess 17 of the valve 15 with the outlet 51 in connection. Furthermore, the line 36 extends through the recess 20 of the valve and the lines 50, 49, 47 with the auxiliary reservoir 22 in connection. The drive piston 1 and the rod 3 therefore move together depending on the pressure difference between the Brake control line 24 and the auxiliary reservoir 22.

In the position of the direct brake release, the functioning of the system is as follows: In the starting position, compressed air is supplied from the brake control line 24 ai of the chamber 25 and thus through the channel 27, the recess 28, the lines 29 and 30, the recess 19 arranged within the rotating parts of the switching valve 15, the calibrated constriction 48 and the lines 49 and 47 to the auxiliary reservoir 22. At the same time, the auxiliary reservoir is standing 22 via line 50, the innejialb of the valve element

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Mentes of the switching valve 15 arranged recess 20 and the line 36 with the arranged below the drive piston 1 Chamber 37 in connection.

In this position, the control reservoir 23 is separated from the other chambers with the aid of the valve element, the switching valve 15 closing the line; Any connections to the valve I ¹ * of the control reservoir regulating device and its associated chambers are also cut by the valve element of the switching valve 15 in the line 34.

The brake cylinder 21 is accordingly above the outlet line 38 and the arranged inside the rod 3 bore 39 with the Outlet opening 5 in connection.

As soon as the system has its full operating pressure within the brake control line 27, the drive piston 1 will sag the opposing ones prevailing within the chambers 25 and 37 arranged above and below the piston Pressures - i.e. the pressures prevailing within the brake control line 24 and the auxiliary reservoir 22 - are in equilibrium.

The braking process is triggered by a vacuum prevailing within the brake control line 24. Those inside the auxiliary reservoir 22 and the chamber below the drive piston 1 present compressed air begins through the line 49, the

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calibrated constriction 48, which is located within the valve element of the Switching valve 15 existing recess 19, the lines 30 and 29, the recess 28, the channel 27 and the chamber 25 back to flow to the brake control line 24. However, because of the constriction 48, a pressure difference between the chamber 27 and 25 prevails, the drive piston 1 moves upwards.

This upward movement of the drive piston 1 lifts with the help of the Rod 3 the compensation piston 2, whereby the connection between the brake cylinder 21 and the outlet opening 5 is interrupted is as soon as the rod 3 comes into contact with the outlet valve 7 and the bore 39 closes. At the same time, the between the auxiliary reservoir 22 and the brake control line 24 interrupted the existing connection as soon as the within the Rod 3 arranged recess 28 comes out of the area of the channel 27.

Upon further upward movement of the rod 3, the inlet valve 6 opens, so that compressed air from the auxiliary reservoir 22 flows through line 47, inlet valve 6 and outlet line 38 into brake cylinder 21.

As soon as the in the auxiliary reservoir 22 and also below the Drive piston 1 in the chamber 37 pressure due to the supply of compressed air to the brake cylinder 21 on a substantially the same or slightly lower value than the pressure prevailing in the brake control line 24 has fallen, the piston 1 and the rod 3 move downwards again,

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until the inlet valve 6 is closed. The supply of compressed air to the brake cylinder 21 is then interrupted, but without this the pressure relief valve 7 is opened, which corresponds to the "neutral braking position".

When the pressure in the brake control line 24 drops further, the piston 1 moves upwards again, whereby the inlet valve 6 is opened again and further compressed air is supplied to the brake cylinder until the pressure within the auxiliary reservoir 22 drops to a slightly lower value than that within the Brake control line 24 pressure has fallen. This process is continued l "r?, Re, until the in * s" ilfsreservoir 22 and the brake cylinder 21 prevailing pressures are equal and the brake cylinder pressure has reached its maximum value.

As soon as the vacuum prevailing within the brake control line 24 has been eliminated, the pressure prevailing within the chamber 25 above Λ of the drive piston 1 rises and the equilibrium of the piston 1 is disturbed. The piston 1 then moves from its neutral braking position to the brake release position, in which the discharge valve 7 is opened and the compressed air present within the brake cylinder 21 escapes into the atmosphere through the bore 39 made within the rod 3 and the outlet opening 40.

It should be noted that the escape within the brake

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cylinder 21 is fully discharged and the brake is completely released, this process taking place even if the pressure present within the brake control line 24 shows a further increase is exposed.

As soon as the rod 3 is moved from its neutral braking position to the brake release position, the chamber 25, the channel 27, the recess 28, the lines 29 and 30, the recess 19 arranged within the switchover valve 15, the calibrated constriction 48, the lines 49 and 47 a connected connection between the brake control line 24 and the auxiliary reservoir 22 the auxiliary reservoir 22 is again supplied with compressed air from the brake control line 24.

A modified embodiment according to the invention is shown in Figs. Gures 3 and 4 shown, which differs from the embodiment of Figure 1 and 2 only in that the switchover from the position of a gradual to the direct brake release is electrical an electrically operated switch valve 15 is arranged, however carries out the same connections as the latter * Apart from the switching valve 52, the system shown in FIG Figure 1 is very similar to the system shown, the same reference numerals have been used to represent the same or corresponding parts.

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to deliver.

The switching valve 52 has a plunger coil having a winding 53 and an actuation element 5 ^a ^ uf. The actuating element 54 is connected via a branching piece 55 to 2 axially displaceable valve elements 56 and 57, which have pistons 58 - 61 and 2 - 65 arranged at certain distances from one another. These two valve elements are actuated with the aid of compression springs 66 and 6? held in the upper position shown in FIG.

Figure 3 shows the switching valve 52 in the position for gradual discharge. The winding 53 of the plunger coil is de-energized, the actuating element 5 ^ together with the distribution piece 55 and the valve elements 56, 51 under the action of the compression springs 66, 67 in its upper position is held.

The functioning of the system is the same as in the system according to FIG. 1, with a connection between the various Chambers is caused by the recesses arranged between the pistons of the valve elements 56. These recesses have the same function as the recesses 16-20 of the valve 15 shown in FIG

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The same reference numerals are denoted. The recess 20 arranged in the valve element of the switching valve 15 according to FIG standing inlet opening 20 and with the lines 35, 36 in communication recesses 20a, 20b replaced.

FIG. 4 corresponds to FIG. 2 and shows the valve 52 in the position of the direct brake release, in which position it is is moved by energizing the plunger coil by connecting the lines 68, 69 to a suitable DC voltage source. As a result, the actuating element 54 together with the branch 55 and the valve elements 56, 57 pressed against the action of the compression springs 66, 67 in its lower position.

The system now works in the same way as has already been described with reference to Figure 2, the same connections of the various chambers effected by the recesses 16 and 20 are achieved. In the the valve element of the switching valve 15 arranged recess 20 according to Figure 2 is now, for example, by a Recess 20b is obtained, which corresponds to the lines 36, 50 in the lower position of the valve element 57 stands.

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Figures 5 and 6 show a further embodiment, in which the switch from gradual to direct brake release by an electro-pneumatically operated valve 52 is effected. Apart from the switching valve, that is shown in FIG The system is entirely equivalent to the embodiments shown in FIGS. 1 and 3.

The switching valve has Ventileleraente 56, 57 with corresponding Recesses to form the same connections between the various chambers according to the FIGS. 3 and 4 Manufacture shown embodiment. In the present embodiment, however, the valve elements 56, 57 are included a pneumatically operated piston 7 ^ connected, which is displaceable is arranged within a cylinder 73. This is connected to a pressurized gas source via a plunger-operated valve or an outlet opening in connection. The switching valve 52 accordingly has a valve stem 70, which is connected to the actuating element of the plunger coil and which an inlet valve 71 and at suitable intervals an outlet valve 72 for controlling the pressure in the cylinder 73 arranged above the piston 7 ^.

When the changeover valve 52 is in the position for gradual brake release shown in FIG Winding 53 of the plunger coil valve de-energized, and the actuating element 5 ^ together with the valve stem 70 under the

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Effect of a weak one arranged below the ram Spring 75 in its upper position, in which the inlet valve 71 is closed and the outlet valve 72 is open.

The chamber 73 arranged above the piston 7k is thus in communication with the atmosphere via a channel 76, the discharge valve 72 and an outlet opening 77, so that the valve elements 56, 57 and the piston 7 ^ under the action of the springs 66, 67 with their be held in the raised position. With the valve elements 57 in this position, the system operates in the same way as has been described with reference to FIG. In order to bring the switching valve 52 into the position of the direct brake release, the winding 53 of the plunger coil valve is energized, whereby the actuating element 5 * t and the valve stem 70 are moved downwards. The discharge valve 72 is closed and the inlet valve 71 is opened. The compressed air present in the auxiliary reservoir 22 can thus pass through the valve 71 and the channel 76 to the cylinder 73, whereby the piston 7 ^ is guided downwards and the valve elements 56, 57 are brought into their lower position shown in FIG. The system then operates in the manner already described with reference to FIG.

If so desired, the cylinder 73 can be supplied from a source of pressurized gas, if any, other than that Auxiliary reservoir 22 be fed.

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Other arrangements for actuating the switch valve can also be used. For example, the actuation can take place purely pneumatically, in that a certain pressure state prevailing within the brake control line Zk is provided for the switchover. Finally, the switchover can also take place in that the brake control line 2k is briefly exposed to a specific vacuum.

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Claims (8)

Claims 1. Pressure medium distributor for controlling a pressure medium brake, consisting of an output line connected to a brake cylinder and a brake control device which can be actuated as a function of the pressure difference between the brake control line and a control pressure, whereby an auxiliary pressure medium reservoir with the output line for the actuation of the brake on the one hand and the Ausgapgsleitung with an outlet opening for the release of the brake on the other hand can be brought into connection, thereby characterized in that a switch valve (15, 52) is provided which has a position for gradual brake release (Figures 1, 3.5), in which the control pressure is the pressure prevailing within a pressure medium control reservoir (23) and the pressure Output line (38) is connected to a pressure medium actuating element counteracting the movement of the control element (1, 2, 3) in the direction of a brake actuation and 109852/0044 that the switching valve (15, 52) has a position for direct Breras solution (Figures 2, 4, 6), in which the Control pressure that prevails within an auxiliary reservoir i22) Pressure is and the actuating element (2, ^ 5) ineffective is made 2. System according to claim 1, characterized in that the actuating element (2 ^ 5) is rendered ineffective by the compound having an A discharge port (31) through the valve elements (15, 17) in the position of the direct Breraslösung. 3. System according to claim 1 or 2, characterized in that geker-nzelch ~ net that the valve part (15) is a manually operable valve. * +. System according to claim 1 or 2, characterized in that the valve (51) at least one movable valve member (56, 57) which is connected to an electrically operated ™-actuated element (53 "5 ² O, and that the valve element ( 56, 57) can optionally be switched between a position of gradual and direct brake release. 5. System according to one of claims 1 to ^, characterized in that that the valve element between 2 positions with the help of a pressure medium valve actuation element (73, 7 * 0 is adjustable. 109852 / ÖOU 6. System according to claims 4 and 5, characterized in that the electrical actuating element (53, 5 ² O controls the supply of pressure medium to the Druckmittelventilbetätlgungselement (73, 74). 7. System according to claim 5 or 6, characterized in that the actuation of the valve actuating element causing pressure medium is supplied from the auxiliary reservoir (22). 8. System according to any one of the preceding claims, characterized in that the transition of the switching valve of the position of a gradual to the direct brake release with the help of valve elements takes place under the action of the brief pressure conditions in the brake control line (24) are operable. 9 · System according to one of claims 1-7, characterized in that the valve elements for switching over from gradual for direct brake release is effected by a vacuum within the brake control line (24). 109852 / OOU